Different radio network systems that may offer different telecommunications services are typically deployed separately from each other. As an example, third generation (3G) wireless systems are being deployed in the 2 GHz International Mobile Telephony (IMT)-2000 frequency allocations in accordance with International Telecommunications Union (ITU) standards. Wideband code division multiple access (WCDMA) is an example of a third generation wireless technology. WCDMA has a number of variations, including direct spread with frequency division duplex (in which the uplink and the downlink are separated in frequency), direct spread with time division duplex (in which the uplink and the downlink are separated by time), and multiple carrier CDMA. Direct spread-frequency division duplex WCDMA typically utilizes a 5 MHz bandwidth or a multiple of a 5 MHz bandwidth. Third generation wireless systems may utilize technologies in accordance with different standards, including cdma2000. Cdma2000 is a variation of a multiple carrier CDMA technology and is compatible with second generation wireless systems that are operating in North America. Moreover, second generation (2G) wireless systems are operating around the world. In Europe, second generation wireless systems typically comply with global systems for communications (GSM) standards, which are based on a time division multiple access technology. In North America and Korea, second generation wireless systems are operating in accordance with cdmaOne, which is based on a code division multiple access technology.
FIG. 1 shows a system of base stations 101, 103, 105, 107, and 109 that support global system for mobile communications (GSM) that are synchronized by a global positioning system (GPS) reference system 111 in accordance with prior art. Base stations 101–109 service geographical areas 102, 104, 106, 108, and 110, respectively. Global positioning system (GPS) 111 provides a time reference 113 for base stations 101–109. Time reference 113 may be used to synchronize base stations 101–109 to a common time base and to adjust reference oscillators that control the center frequencies of radios that are associated with base stations 101–109. The time base may be used to establish the timing for a time division multiple access system (TDMA) structure. Frequency adjustment may be needed to correct drifting for the center frequencies that are associated with base stations 101–109, in which the frequency drifting may cause interference with geographical areas 102–110.
FIG. 2 shows a system of single frequency network (SFN) base stations 201 and 203 that are synchronized by global positioning system reference system 111 in accordance with prior art. Single frequency network base stations 201 and 203 may support a direct spread wideband code division technology, in which a plurality of wireless terminals is simultaneously utilizing the same frequency spectrum. Base stations 201 and 203 support geographical areas 202 and 204, respectively. Global positioning system 111 provides time reference 113 to synchronize transmissions from base stations 201 and 203. Time reference 113 may also be used to correct drifting of local oscillators that control the center frequencies of radios in base stations 201 and 203.
In parallel with the deployment of second and third generation wireless systems, digital video broadcasting (DVB) is being deployed in different parts of the world. Digital video broadcasting standards support the broadcast of digital television content as well as other digital information, e.g. Internet web content. Terrestrial digital video broadcasting (DVB-T), for example, may utilize very high frequency (VHF) or ultra high frequency (UHF) frequency bands with orthogonal frequency division multiplexing (OFDM) modulation, which is based on multi-carrier modulation. DVB-T is largely designed for unidirectional, broadcast, and multicast media delivery, in which the frequency bandwidth is sufficiently large to support data rates as much as 32 Mbps on the downlink (base station to wireless terminal). Other standards that are being adopted throughout the world are also applicable, including Integrated Services Digital Broadcasting-Terrestrial transmission (ISDB-T) and Digital Television (DTV).
FIG. 3 shows two different radio networks that are synchronized by different reference oscillators in accordance with prior art. A radio network 301 comprises a radio 307 and a reference oscillator 305. A radio network 303 comprises radios 311, 313, and 315 and a reference oscillator 309. Reference oscillator 305 adjusts a centegr frequency f1 for radio 307. Reference oscillator 309 adjusts center frequencies f2, f3, and f4 for radios 311, 313, and 315, respectively. Radio network 301 may support a wideband CDMA technology such as WCDMA, while radio network 303 may support a different radio technology and telecommunications service such as terrestrial digital video broadcasting. Typically, center frequency f1 is significantly removed from center frequencies f2, f3, and f4. (With WCDMA and DVB-T, as illustrated in the example above, radio network 301 may utilize frequency spectrum at approximately 2 GHz while radio network 303 may utilize a frequency spectrum in the UHF band, e.g. channel 40 that corresponds to approximately 626 MHz). Because of the disparity of center frequencies, radio network 301 and radio network 303 utilize separate reference oscillators.
As illustrated in example above, different radio networks are being deployed that are not integrated either from a service provider's or from a user's perspective. Different radio systems may utilize different center frequencies and different frequency bandwidths, while having different symmetry configurations. For example, a WCDMA system may be deployed in the 2 GHz spectrum, utilizing direct spread CDMA with approximately equivalent data rates on the uplink (wireless terminal to base station) and downlink (base station to wireless terminal), while a DVB-T system may be deployed in the UHF television frequency spectrum that utilizes OFDM modulation with a high data rate on the downlink. Moreover, in order to support both DVB-T and WCDMA, a wireless terminal requires two separate radio frequency (RF) front-ends. Thus, providing different telecommunications services to a user may be inefficient and complex.
Integrating different radio network systems may facilitate the support of different telecommunication services to a user. For example, cellular radio services are almost ubiquitous throughout the word. Moreover, broadband, multicast video services are being developed and may soon be widely deployed. Of course, a user wishes to have a single wireless terminal even though the user may subscribe to a plurality of telecommunication services that may be supported by different radio networks. Consequently, a method and apparatus that integrates associated radio networks are beneficial in advancing the art in support of these telecommunication services.